1. Field of the Invention
The invention relates to a method for producing a moulded part provided with a through-hole as well as a device for performing the method of producing a moulded part provided with a through-hole.
2. Description of Related Art
Such a method is known for example from DE 31 47 897 A1. According to this document, the mass production of identical annular metallic parts takes place proceeding from a metallic, rod-shaped blank by the compression and thereby effected deformation of an end region of the blank to form a disc and by subsequent axial puncturing of the disc by means of a punch having the same cross-sectional shape as the (uncompressed) blank and severing of the disc core punctured by the punch from the disc. The disc core in one piece with the uncompressed blank segment forms together with the latter the starting point for a further process cycle until such time as the remaining part of the blank is no longer sufficient for the formation of further-moulded parts and is lost as waste.
During the puncturing of the disc core, an undesired fracture surface with cracks and at best burrs, which may require reworking of the moulded parts, is formed at the peripheral edge of the through-hole thereby produced in the disc on account of the shearing and tensile stresses taking effect.
The problem underlying the invention therefore is to improve a method of the type mentioned at the outset in such a way that the moulded parts thereby produced do not require reworking or at least greatly reduced reworking. In particular, the moulded parts should not exhibit any substantial fractures, burrs or other deformations in the region of their produced through-hole.
This problem is solved by the method according to an embodiment of the invention and the device according to an embodiment of the invention. Particularly advantageous developments and embodiments of the invention are described herein.
“Rod material” is understood in the present connection to mean any form of material with a pronounced longitudinal extension and an arbitrary cross-section that is constant over the longitudinal extension. In particular, rods, bars and wires having any dimensions fall under this definition. Circular cross-sections are the rule, but the invention is not limited thereto. The term “rod-shaped” is to be understood similarly. “Disc” is to be understood in the present connection as any body shape widened in the cross-sectional dimensions compared to the blank. Flat discs with, in particular, a circular external contour are the rule, but the invention is not limited thereto.